Chemistry and Physics. 385 



The other salts belonging to type III have magnesium, man- 

 ganese and nickel in place of calcium, and in one instance cu- 

 prous copper in place of silver. The replacements of barium by 

 strontium and silver by copper give the other members of type lY. 

 The four members of the latter type are isomorphous and resemble 

 apophyllite in form. — Amer. Chem. Jour., xxviii, 245. h, l. tv. 



5. The Determination of Thallium in the Thallous State. — To 

 make this determination Thomas adds auric bromide solution in 

 excess to the warm thallous solution, then keeps the liquid warm 

 for eight or ten hours, and finally filters off the metallic gold 

 which is produced and weighs it. Three molecules of the thal- 

 lous salt precipitate two atoms of gold. The test-analyses given 

 are very satisfactory. The method will evidently be useful in 

 analyzing substances containing both thallous and thallic com- 

 pounds. — Bull. Soe. Chim., xxvii, 470. h. l. w. 



6. Chemisches Praktihum, von Dr. A. Wolfeijm. 12mo, pp. 

 562. Leipsic, 1902 (Engelmann). — This volume is the first 

 part, dealing with analytical operations, of a guide in laboratory 

 work. The course is designed on a practical basis with the object 

 of giving the student an idea of factory operations, and of en- 

 couraging the study of technical chemistry. This feature will 

 doubtless appear still more conspicuously in the second part, not 

 yet published, which will deal with chemical preparations. The 

 volume under consideration covers a wide field of analytical 

 chemistry in a very compact form. It embraces a course in 

 quantitative analysis for the common metals and acid radicals, as 

 well as the detection of the more important groups in organic 

 compounds and the application of these tests to a large number 

 of natural and artificial organic products. Quantitative analysis 

 is presented in all its branches ; not only the gravimetric and 

 volumetric methods for determining inorganic substances are 

 included, but also the quantitative determination of organic 

 groups, gas analysis, molecular weight determination, toxicologi- 

 cal analysis, and many methods of technical analysis. The 

 methods appear to be well chosen, so that the book will be use- 

 ful, not only to students pursuing courses in laboratory work, 

 but also to analytical and technical chemists. h. l. w. 



7. Vacuum Thermo Element. — Petek Lebedew discusses the 

 advantages of enclosing a thermo element in rarified air. Kundt 

 and Marbury have shown that a body loses heat less rapidly in a 

 vacuum, and this fact doubtless lies at the root of the superior 

 efficiency of a bolometer or thermo element in a vacuum. The 

 author employs a thermo element of platinum constantin, diam- 

 eter of the wire ^=: 0*025™™. The sensibility steadily increases 

 and reaches its highest point at a pressure of O'Ol™™. It is 

 believed that this method will allow measurements of electrical 

 waves, which hitherto could not be made. — Ann. der Physik^ No. 

 9, 1902. pp. 209-213. J. T. 



8. Electromotive Force of Ozone. — In the course of an investiga- 

 tion on the possibility of converting the heat of deozonization 



